use try-with-resources statement

Author: Vincent Potucek

spring-context-support/src/main/java/org/springframework/mail/javamail/JavaMailSenderImpl.java

@@ -342,14 +342,7 @@ public void send(MimeMessage... mimeMessages) throws MailException {
 	 * for. Throws a {@link MessagingException} if the connection attempt failed.
 	 */
 	public void testConnection() throws MessagingException {
-		Transport transport = null;
-		try {
-			transport = connectTransport();
-		}
-		finally {
-			if (transport != null) {
-				transport.close();
-			}
+		try (Transport ignored = connectTransport()) {
 		}
 	}
 

spring-core/src/main/java/org/springframework/cglib/core/DuplicatesPredicate.java

@@ -89,14 +89,12 @@ public DuplicatesPredicate(List allMethods) {
             continue;
           }
           InputStream is = cl.getResourceAsStream(c.getName().replace('.', '/') + ".class");
-          if (is == null) {
-            continue;
-          }
-          try {
-            new ClassReader(is).accept(finder, ClassReader.SKIP_FRAMES | ClassReader.SKIP_DEBUG);
-          } finally {
-            is.close();
-          }
+			try (is) {
+				if (is == null) {
+					continue;
+				}
+				new ClassReader(is).accept(finder, ClassReader.SKIP_FRAMES | ClassReader.SKIP_DEBUG);
+			}
         } catch (IOException ignored) {
         }
       }

spring-core/src/main/java/org/springframework/cglib/proxy/BridgeMethodResolver.java

@@ -63,16 +63,14 @@ public BridgeMethodResolver(Map declToBridge, ClassLoader classLoader) {
             Set bridges = (Set) entry.getValue();
             try {
                 InputStream is = classLoader.getResourceAsStream(owner.getName().replace('.', '/') + ".class");
-                if (is == null) {
-                    return resolved;
-                }
-                try {
-                    new ClassReader(is)
-                            .accept(new BridgedFinder(bridges, resolved),
-                                    ClassReader.SKIP_FRAMES | ClassReader.SKIP_DEBUG);
-                } finally {
-                    is.close();
-                }
+				try (is) {
+					if (is == null) {
+						return resolved;
+					}
+					new ClassReader(is)
+							.accept(new BridgedFinder(bridges, resolved),
+									ClassReader.SKIP_FRAMES | ClassReader.SKIP_DEBUG);
+				}
             } catch (IOException ignored) {}
         }
         return resolved;

spring-core/src/main/java/org/springframework/cglib/transform/AbstractClassLoader.java

@@ -61,20 +61,16 @@ public Class loadClass(String name) throws ClassNotFoundException {
                        name.replace('.','/') + ".class"
                   );
 
-           if (is == null) {
+			try (is) {
+				if (is == null) {
 
-              throw new ClassNotFoundException(name);
+					throw new ClassNotFoundException(name);
 
-           }
-           try {
+				}
 
-              r = new ClassReader(is);
+				r = new ClassReader(is);
 
-           } finally {
-
-              is.close();
-
-           }
+			}
         } catch (IOException e) {
             throw new ClassNotFoundException(name + ":" + e.getMessage());
         }

spring-core/src/main/java/org/springframework/core/io/AbstractResource.java

@@ -153,8 +153,7 @@ public ReadableByteChannel readableChannel() throws IOException {
 	 */
 	@Override
 	public long contentLength() throws IOException {
-		InputStream is = getInputStream();
-		try {
+		try (InputStream is = getInputStream()) {
 			long size = 0;
 			byte[] buf = new byte[256];
 			int read;
@@ -163,14 +162,6 @@ public long contentLength() throws IOException {
 			}
 			return size;
 		}
-		finally {
-			try {
-				is.close();
-			}
-			catch (IOException ex) {
-				debug(() -> "Could not close content-length InputStream for " + getDescription(), ex);
-			}
-		}
 	}
 
 	/**

spring-jdbc/src/main/java/org/springframework/jdbc/datasource/embedded/AbstractEmbeddedDatabaseConfigurer.java

@@ -40,31 +40,15 @@ abstract class AbstractEmbeddedDatabaseConfigurer implements EmbeddedDatabaseCon
 
 	@Override
 	public void shutdown(DataSource dataSource, String databaseName) {
-		Connection con = null;
-		try {
-			con = dataSource.getConnection();
+		try (Connection con = dataSource.getConnection()) {
 			if (con != null) {
 				try (Statement stmt = con.createStatement()) {
 					stmt.execute("SHUTDOWN");
 				}
 			}
-		}
-		catch (SQLException ex) {
+		} catch (SQLException ex) {
 			logger.info("Could not shut down embedded database", ex);
 		}
-		finally {
-			if (con != null) {
-				try {
-					con.close();
-				}
-				catch (SQLException ex) {
-					logger.debug("Could not close JDBC Connection on shutdown", ex);
-				}
-				catch (Throwable ex) {
-					logger.debug("Unexpected exception on closing JDBC Connection", ex);
-				}
-			}
-		}
 	}
 
 }

spring-jdbc/src/main/java/org/springframework/jdbc/datasource/init/ScriptUtils.java

@@ -253,8 +253,7 @@ public static void executeSqlScript(Connection connection, EncodedResource resou
 					blockCommentEndDelimiter, statements);
 
 			int stmtNumber = 0;
-			Statement stmt = connection.createStatement();
-			try {
+			try (Statement stmt = connection.createStatement()) {
 				for (String statement : statements) {
 					stmtNumber++;
 					try {
@@ -270,27 +269,19 @@ public static void executeSqlScript(Connection connection, EncodedResource resou
 								warningToLog = warningToLog.getNextWarning();
 							}
 						}
-					}
-					catch (SQLException ex) {
+					} catch (SQLException ex) {
 						boolean dropStatement = StringUtils.startsWithIgnoreCase(statement.trim(), "drop");
 						if (continueOnError || (dropStatement && ignoreFailedDrops)) {
 							if (logger.isDebugEnabled()) {
 								logger.debug(ScriptStatementFailedException.buildErrorMessage(statement, stmtNumber, resource), ex);
 							}
-						}
-						else {
+						} else {
 							throw new ScriptStatementFailedException(statement, stmtNumber, resource, ex);
 						}
 					}
 				}
-			}
-			finally {
-				try {
-					stmt.close();
-				}
-				catch (Throwable ex) {
-					logger.trace("Could not close JDBC Statement", ex);
-				}
+			} catch (Throwable ex) {
+				logger.trace("Could not close JDBC Statement", ex);
 			}
 
 			long elapsedTime = System.currentTimeMillis() - startTime;

spring-jms/src/main/java/org/springframework/jms/listener/AbstractPollingMessageListenerContainer.java

@@ -316,21 +316,19 @@ protected boolean doReceiveAndExecute(Object invoker, @Nullable Session session,
 				boolean exposeResource = (!transactional && isExposeListenerSession() &&
 						!TransactionSynchronizationManager.hasResource(obtainConnectionFactory()));
 				Observation observation = createObservation(message).start();
-				Observation.Scope scope = observation.openScope();
-				if (logger.isDebugEnabled()) {
-					logger.debug("Received message of type [" + message.getClass() + "] from consumer [" +
-							consumerToUse + "] of " + (transactional ? "transactional " : "") + "session [" +
-							sessionToUse + "]");
-				}
-				try {
+				try (Observation.Scope ignored = observation.openScope()) {
+					if (logger.isDebugEnabled()) {
+						logger.debug("Received message of type [" + message.getClass() + "] from consumer [" +
+								consumerToUse + "] of " + (transactional ? "transactional " : "") + "session [" +
+								sessionToUse + "]");
+					}
 					messageReceived(invoker, sessionToUse);
 					if (exposeResource) {
 						TransactionSynchronizationManager.bindResource(
 								obtainConnectionFactory(), new LocallyExposedJmsResourceHolder(sessionToUse));
 					}
 					doExecuteListener(sessionToUse, message);
-				}
-				catch (Throwable ex) {
+				} catch (Throwable ex) {
 					if (status != null) {
 						if (logger.isDebugEnabled()) {
 							logger.debug("Rolling back transaction because of listener exception thrown: " + ex);
@@ -339,8 +337,7 @@ protected boolean doReceiveAndExecute(Object invoker, @Nullable Session session,
 					}
 					try {
 						handleListenerException(ex);
-					}
-					catch (Throwable throwable) {
+					} catch (Throwable throwable) {
 						observation.error(throwable);
 						throw throwable;
 					}
@@ -349,13 +346,11 @@ protected boolean doReceiveAndExecute(Object invoker, @Nullable Session session,
 					if (ex instanceof JMSException jmsException) {
 						throw jmsException;
 					}
-				}
-				finally {
+				} finally {
 					if (exposeResource) {
 						TransactionSynchronizationManager.unbindResource(obtainConnectionFactory());
 					}
 					observation.stop();
-					scope.close();
 				}
 				// Indicate that a message has been received.
 				return true;

spring-orm/src/test/java/org/springframework/orm/jpa/hibernate/HibernateMultiEntityManagerFactoryIntegrationTests.java

@@ -58,14 +58,10 @@ protected void testEntityManagerFactoryImplementsEntityManagerFactoryInfo() {
 
 	@Test
 	void testEntityManagerFactory2() {
-		EntityManager em = this.entityManagerFactory2.createEntityManager();
-		try {
+		try (EntityManager em = this.entityManagerFactory2.createEntityManager()) {
 			assertThatIllegalArgumentException().isThrownBy(() ->
 					em.createQuery("select tb from TestBean"));
 		}
-		finally {
-			em.close();
-		}
 	}
 
 }

spring-web/src/main/java/org/springframework/http/converter/ResourceHttpMessageConverter.java

@@ -152,22 +152,16 @@ protected void writeContent(Resource resource, HttpOutputMessage outputMessage)
 		// We cannot use try-with-resources here for the InputStream, since we have
 		// custom handling of the close() method in a finally-block.
 		try {
-			InputStream in = resource.getInputStream();
-			try {
-				OutputStream out = outputMessage.getBody();
-				in.transferTo(out);
-				out.flush();
-			}
-			catch (NullPointerException ex) {
-				// ignore, see SPR-13620
-			}
-			finally {
+			try (InputStream in = resource.getInputStream()) {
 				try {
-					in.close();
-				}
-				catch (Throwable ex) {
-					// ignore, see SPR-12999
+					OutputStream out = outputMessage.getBody();
+					in.transferTo(out);
+					out.flush();
+				} catch (NullPointerException ex) {
+					// ignore, see SPR-13620
 				}
+			} catch (Throwable ex) {
+				// ignore, see SPR-12999
 			}
 		}
 		catch (FileNotFoundException ex) {